This invention relates to a motor assist control apparatus for a hybrid vehicle which can realize smooth acceleration on the basis of a decision by the driving person during traveling of a hybrid vehicle. The apparatus can improve drive-ability, and does not require an exclusive map, and thus can contribute to simplification of a control system.
Some motor vehicles are of a type commonly called a hybrid vehicle having an internal combustion engine and an electric motor disposed therein as the power sources of a propulsion system. The engine mounted on the hybrid vehicle is directly connected to an electrical motor having a vehicle driving function and an electrical power generating function. The hybrid vehicle has a motor assist control apparatus to control both driving and power-generating states of the motor based on a driving state of the vehicle and a driving state of the engine.
One such example of a control apparatus of a hybrid vehicle is disclosed in published Japanese Application Laid-Open No. 9-58295. The motor assist control apparatus in this disclosure includes a motor connected with an engine output shaft, and a hand-operated switchover means to perform switchover for more than one mode. An accelerator detecting means detects a quantity of accelerator operation, and a control means controls an output torque characteristic of said motor for a quantity of accelerator operation according to a mode set by hand-operated switchover means.
In a hybrid vehicle, a motor assist control apparatus controls so as to continue an assist of an engine by driving a motor for a vehicle when a throttle valve of an engine, in particular, is fully opened in high load driving operation. The motor assist control apparatus can also control so as to execute an assist of an engine by driving a motor for a vehicle at an initial term only in high load driving operation of the engine.
In a first mode, to continue an assist by a motor for a vehicle in high load driving of an engine depends on deciding to drive a motor for a vehicle so long as the volume of a battery of a motor for a vehicle is permitted. In a second mode, to execute an assist by a motor for a vehicle at only an initial term in high load driving of an engine depends on deciding to control consumption of a battery by asynchronously driving the motor.
In the first mode, there is a problem in that a motor for a vehicle cannot drive when a battery is completely discharged. In the second mode, there is the problem that an engine may not always fully receive a benefit of assist by a motor for a vehicle because a battery has a large amount of electric power.
Accordingly, a traditional motor assist control apparatus for a hybrid vehicle cannot realize an assist by a motor on the basis of a decision by a driving person during traveling of the vehicle, and cannot realize smooth acceleration. Consequently, drive-ability cannot be improved.
Moreover, in the motor assist control apparatus disclosed in published Japanese Application Laid-Open No. 9-58295, there is a problem in that an excessive electric discharge of a battery can occur because in one mode selected by a hand-operated switchover means, the battery is forcibly controlled.
In order to obviate or minimize the above problems the present invention provides a motor assist control apparatus for a hybrid vehicle having an engine and an electric motor disposed therein. The electric motor has both driving and power-generating functions and is directly connected to the engine mounted on the hybrid vehicle. The control apparatus includes an engine rotational speed detecting means, an engine load detecting means, a first map used in order to execute power-generating operation of the motor by searching power-generation operating torque order values in response to detected engine rotational speed and engine load detected from accelerator means during traveling of the hybrid vehicle. A second map is used in order to execute driving operation of the motor by searching for a drive operating torque order value in response to both the engine rotational speed and engine load, when the detected load has exceeded a set value during traveling of the hybrid vehicle and a use demand input switch issues a second map use demand input signal by manual operation. A controller executes both drive and power-generating operations of the motor based on a driving state of the hybrid vehicle and a driving state of the engine, and executes a drive operation for the vehicle switching over use to the second map when the second map use demand signal is input and when second map use conditions are satisfied.
In this invention, the motor assist control apparatus for a vehicle executes both drive and power-generating operations of a motor for a vehicle based on a driving state of a hybrid vehicle and a driving state of an engine, and by use demand input means. The apparatus executes drive operation of the motor by switching over use to a second map when the second map use demand signal is input and when the second map use condition is satisfied. Accordingly, while the motor assist control apparatus controls consumption for a main battery that supplies electric power to the motor during traveling of the hybrid vehicle, in a formation region of the second map use condition, an assist for the engine by the motor on the basis of a selection by a driving person can be realized by using the second map. An assist by the motor on the basis of the will of a driving person can also be realized by utilizing first and second maps for existing common map control.